"This badge knows what talks you go to. It knows who you talk to. It knows what places in the conference you go. It knows when you were there," says Rob Zinkov, of the HOPE badge team.

The HOPE badge was meant to be hacked and let people flash the firmware. "It really appeals to people in both hardware and software," says Zinkov. The basic badge is an active RFID that can report itself and read other active RFIDs up to 60 ft away, all in a tiny and entirely open source package. It has a small bit of memory that lets it take down other badge ID numbers for later, and eight sensors the wearer can press with a finger.

Attendee Adam Mayer hacked his badge to let him steal the identity of anyone whose badge reported to his own, and walked around the social system as them for a few minutes before stealing the next identity.

"The badge works on multiple levels," says Aestetix, project manager and pointy haired boss of the AMD badge project. It allows its wearer to see what other talks have interested attendees that have attending similar talks, and find friends. "On the flip side, we can take what we learn from it and we can apply that to the next conference." Aestetix pauses, and grins. "There's also the big privacy aspect. We have a system that knows exactly where you were at all times."

The overproduced badges of hacker conferences got started with Defcon's challenge to hack the badge, which generally involves a circuit board and wild imagination. (Last year's entries included attaching a Geiger counter to the badge and using three badges to fly a robotic blimp—and those were the losers.)

The other parent of the HOPE badge is the Sputnik experiment from the 23rd Chaos Computer Congress in Berlin in 2006, where roughly 1000 attendees wore RFIDs on their badges that reported to 35 stations in the conference, tracking each person's movement. The creators of Sputnik mapped the movements of attendees and put them on display on large monitors.

HOPE went much further, adding in hardware hacking and a website. They wanted to bring in application software as well as firmware and data visualization. HOPE's badge team connected the badge IDs to a social network, allowing for friending, deriving preferences from talk attendance, and letting attendees associate real world data like websites with their in-con personas.

"It's kind of perpetually in alpha stage," says Aestetix. They try to add enough to the badge each HOPE that it never quite works right, and stretches both the hackers putting on the conference and the hackers getting the badges. Work went into the badge through much of the year.

Zinkov used the social network data attendees added about themselves to spider their websites and build even more complete data about everyone. Now they are building data visualizations and maps of correlations with conference activity. Anyone can get into the game, too. A torrent of the 8GB of collected data is publicly available. (Last year's data weighed in at only 20MB.)

The Hackers on Planet Earth conference is an outsized 2600 meeting that happens every two years in New York. It's come a long way in its time, ideas of hacking expanding from software to hardware, society, food and even sex. Quinn Norton is reporting from New York.